Two hundred and three people were poisoned after having breakfast at a hospital restaurant in northeast China's Heilongjiang Province on Monday, and one of them died, hospital sources and the local government confirmed.

The victims include patients and staff members of the Heilongjiang Provincial Hospital of Traditional Chinese Medicine. Most of them complained of nausea and diarrhea shortly after they ate breakfast at the hospital's restaurant.

The most serious case, 77-year-old Du Qingrong, died Monday afternoon. She was hospitalized on Friday for cardiovascular disease.

Hospital sources said all the other victims were out of danger by Monday night.

The restaurant was shut down immediately after the accident and the local health watchdog took samples of the food for lab work on Monday.

All the victims ate porridge, and investigators suspected the water had been contaminated by rat poison.

The hospital is among the largest and best-equipped medical institutions in the provincial capital Harbin.